When a patient is anesthetized with inhalable gaseous anesthesia various devices are used to direct the anesthesia into the patient's lungs. One type device involves a mask that fits over the patient's nose and mouth and connects with an anesthesia machine. Another device includes a nasal cannula where the anesthesia is directed through the nasal passage and into the patient's lungs. Still another, and becoming more widely used, is an endotracheal tube.
An endotracheal tube is essentially a large-diameter tube inserted in through the patient's mouth and fed down through the trachea to where it terminates right above the bronchial branch connected to the lungs. This endotracheal tube is then connected to an anesthesia machine. Many physicians believe that the endotracheal tube method provides a more accurate control of administering the anesthesia to the patient.
When anesthesia is fed through the endotracheal tube in the patient's trachea a structure is required to seal the outer surface of the endotracheal tube with the trachea. This is to keep anesthesia gases from escaping back between the endotracheal tube and the trachea. A common structure for sealing the endotracheal tube to the trachea is an inflatable balloon. This is sometimes called the "cuff" or tracheal balloon of an endotracheal tube. Because the endotracheal tube and balloon are in a tender area of the patient's trachea it is desires that the tube and balloon be made of a nonirritating material. Previous rubber cuffs and tubes had the disadvantage of containing accelerators and vulcanizing agents, which could irritate the trachea.
Preferred endotracheal tubes are made of a thermoplastic or plastisol material that do not require vulcanizing agents and cause less irritation to the patient.
In the past these endotracheal tubes have been made by preforming a plastisol cuff or balloon and then securing this balloon to a flexible tube. One of the major problems in securing the balloon to the tube involved the joint between the balloon and the tube. Because the endotracheal tube must slide down past the vocal cords it is important to make the forward end of the endotracheal tube as smooth as possible. One of the main problems with previous endotracheal tubes was the annular ridge formed at the forward juncture of the inflatable sleeve and the dual-lumen tube. It is to this tube and inflatable balloon joint that this invention relates.